compat/vsnprintf: return number of bytes required on truncation.

This conforms to C99, but requires Windows >= XP.

Signed-off-by: Derek Buitenhuis <derek.buitenhuis@gmail.com>
This commit is contained in:
Ronald S. Bultje 2012-09-14 18:56:46 +00:00 committed by Derek Buitenhuis
parent 3f7fd59d15
commit c1c8fdab46
1 changed files with 10 additions and 3 deletions

View File

@ -26,6 +26,10 @@
#include "libavutil/error.h"
#if !defined(va_copy) && defined(_MSC_VER)
#define va_copy(dst, src) ((dst) = (src))
#endif
int avpriv_snprintf(char *s, size_t n, const char *fmt, ...)
{
va_list ap;
@ -42,9 +46,10 @@ int avpriv_vsnprintf(char *s, size_t n, const char *fmt,
va_list ap)
{
int ret;
va_list ap_copy;
if (n == 0)
return 0;
return _vscprintf(fmt, ap);
else if (n > INT_MAX)
return AVERROR(EOVERFLOW);
@ -55,9 +60,11 @@ int avpriv_vsnprintf(char *s, size_t n, const char *fmt,
* _snprintf/_vsnprintf() to workaround this problem.
* See http://msdn.microsoft.com/en-us/library/1kt27hek(v=vs.80).aspx */
memset(s, 0, n);
ret = _vsnprintf(s, n - 1, fmt, ap);
va_copy(ap_copy, ap);
ret = _vsnprintf(s, n - 1, fmt, ap_copy);
va_end(ap_copy);
if (ret == -1)
ret = n;
ret = _vscprintf(fmt, ap);
return ret;
}